Hydrogenation process for preparing 1, 8-octanedioic acids from certain dilactones with a platinum catalyst



r 2,840,609 Patented J 1958 HYDROGENATION PROCESS FOR PREPARING1,8-OCTANEDIOIC ACEDS FROM CERTAIN DI- LACTONES WITH A PLATINUM CATALYSTJohn C. Sauer, Wilmington, DeL, assignor to E. I. du Pout dc Nernoursand Company, Wilmington, Del., a corporation of Delaware No Drawing.Applicafion September 28, 1956 Serial No. 612,870

8 Claims. (Cl. 260- -537) This invention relates to the production of1,8-octanedioic acids, i. e., suberic acid and substituted subericacids. More particularly this invention relates to a novel catalyticprocess for converting certain dilactones into suberic acid andsubstituted suberic acids.

This application is a continuation-in-part of my copending applicationSer. No. 549,155, filed November 25, 1955, which later application is acontinuation-inpart of my application Ser. No. 432,599, filed May 26,1954, now abandoned.

When acetylenes are reacted with carbon monoxide in the presence of acatalytic amount of a cobalt carbonyl, as described in my copendingpatent application Ser. No. 549,155, filed November 25, 1955, as acontinuation-in-part of Ser. No. 432,599, filed May 26, 1954, nowabandoned, there are obtained new dilacetones corresponding to C (RR) Owherein R and R are hydrogen, haloaryl, alkoxyaryl, or hydrocarbonradicals free from non-aromatic unsaturation, and which show stronglines in the ultraviolet spectra in the region of 3300-4400 A., andyield suberic acids on hydrogenation over platinum in acetic acid. Whenacetylene is reacted with carbon monoxide in the presence of a catalyticamount of cobalt carbonyl, as described in my aforesaid patentapplications there is obtained [A -bifuranl-5,5- dione.

It is an object of this invention to provide a new process for thepreparation of 1,8-octanedioic acids, i. e., suberic acid andsubstituted suberic acids. A further object of this invention is toprovide a novel catalytic process for converting certain dilactones intosuberic acid and substituted suberic acids. A still further object is toconvert abundantly available and relatively inexpensive carbon monoxideand acetylenes in two steps to suberic acid and substituted subericacids. Other objects will appear hereinafter.

These and other objects of this invention are accomplished by thefollowing process for preparing 1,8-octanedioic acids which compriseshydrogenating in an organic.

solvent and in contact with a platinum catalyst a dilactone having theformula C (RR) O whereinR and R are hydrogen, haloaryl, alkoxyaryl ormonovalent hydrocarbon radicals free from non-aromatic unsaturation.This invention particularly provides a novel method for preparingsuberic acid which comprises hydrogenating [A fi -bifuran]-5,5-dione inan organic solvent and in contact with a platinum catalyst.

The dilactones employed as starting materials in this invention aredescribed andjclaimed in my aforesaid ap-. plications Ser. No. 432,599and Ser. No. 549,155, of which said present application is acontinuation-in-part.

The hydrogenation of the dilactone in accordance with this inventiontakes place at ordinary room temperatures, i. e., about 25 C. Ifdesired, however, temperatures below room temperature, i. e., as low as0 C., can be used but under these conditions the reaction is slower.

Likewise, temperatures above room temperature, e. g.

up to 50 C., can be used but this usually has no practical advantage.

The process can be operated at atmospheric pressure, or at pressureswhich are slightly above atmospheric. Since no advantages appear toaccrue from the use of pressures above 500 lb./sq. in., this constitutesa practical upper limit of pressure.

The amount of platinum is at least 0.01% by Weight of the dilactone.Because the rate at which the reaction takes. place is improved byincreasing the catalyst concentration, usually an amount is used which.is in the range of 01-30% by weight of the dilactone being hydrogenated.

Platinum catalysts of various types known to the art can be used. Forinstance, metallicplatinum, or platinum extended on any one of the knownacid-resistant supports can be used. During the process, platinumcompounds, i. e., oxide or salts, are reduced to metallic platinum. Asuitable platinum'catalyst is one prepared by depositing platinumchloride'on charcoal in amount sufiicient to provide 10 g. of platinumper liter of catalyst. This is equivalent to 2% platinum onthe'charcoal.

A'catalyst is prepared by dissolving a'quantity of chloroplatinic acidequivalent to 1.5 g. of platinum in 150 ml. of distilled water. Coconutcharcoal of 4-14 mesh is purified by heating in a stream of hydrogen at450 C. for approximately 20 hours, followed by heating at C. in 10%nitric acid for 6 hours. The charcoal is then washed with distilledwater, dried at 100 C. and the last traces of nitric acid are removed byheating the charcoal for one hour at 450 C. in a stream of nitrogen. Thechloroplatiuic acid is poured over 150 ml. of the purified charcoal andthe mixture is heated on a steam bath until it is dry.

.The hydrogenation of the dilactone is efiected in solution and aceticacid, dioxane, ethyl acetate, tetrahydrofuran, dimethylformamide, andethylene glycol diacetate are convenient media. In place thereof,however,

other polar solvents can be used. The amount of re- EXAMPLE IAresubliined sample (1.8 g.) of [A -bifuran]- 5,5 -dione was placed in aclosed reactor together with'170 ml. of acetic acid and 0.15 g. ofplatinum oxide catalyst. The mixture was then reacted with hydrogen at10 to 27 lb.'/sq. 'in. pressure at room temperature for onehour and 45minutes. Between 4 and 5 mole equivalents of hydrogen were absorbedduring this time. New catalyst, 0.10 g., was then added but absorptionwas very low and slow during the next hour and 40 minutes. The reactionmixture was separated from the catalyst and theacetic acid removed undervacuum. The solid remaining" in the flask was recrystallized from water,M. P. 127 130 C. Infrared analysis indicated almost pure suberic acidwith an impure band at the lactone position. This sample was convertedto the p-toluidide, melting point 210212 C.:A recrystallization fromacetone did not raise ,the melting point to the reported 218 C. value. Amixed melting point with an'authen'tic sample of the p-toluidide showedno depression. The hydrogen 'absorbed in the reaction beyondthatneededfor saturation of'the carbon-carbon double bonds was required forhydrogenolysis of the lacton'elinkages. 1 5

Corresponding substituted suberic acids are obtained analogously fromstarting materials of the formula given above where R and R are otherthan hydrogen atoms.

, EXAMPLE II ran)]-5,5-dione, was hydrogenated in acetic acid, using aplatinum catalyst. The hydrogenation gave a hydrogen number of 0.0360(0..0345),grams hydrogen per gram sample which corresponds closely tothe absorption of moles of hydrogen per mole of sample. The crude acidobtained was converted to the dianilide which melted at 136140 C. andwas found to analyze as follows:

Analysis.-Calculated for C H O N N, 6.4%. Found: N, 6.41%, 6.54%.

The infrared absorption spectra of the dianilide is given in thefollowing table. V

Table 3.05 NH. 3.13. NH. 3.20- NH and/0r :CH. 5.15- 4) group. 5 35;. (45group.

68. probably O=O impurity. O2. amide 0:0. 16 amide or arorn. -C=C-. 24arom. C=O. 47 secondaryamide. 70 arom. -C=O. .65. 13.20 CH of 5,monosubstituted benzene ring. 1315.----. M 14.45- S O-H of s,monosubstituted benzene ring.

EXAMPLE m A reactor was charged with 21.2 g. of the dilactone of ExampleI, 325 ml. of ethylene glycol diacetate, and 0.04 g. of platinum oxidecatalyst. This charge was shaken with hydrogen at 40 lb./sq. in. at roomtemperature. After hydrogen absorption had substantially stopped another0.04 g. of catalyst was added and the hydrogenation continued. Thisprocedure was repeated once more. The total hydrogen absorptioncorresponded to approximately 5 moles of hydrogen per mole of dilactone.The product was filtered to give 8.6 g. of suberic acid, M. P. l41142C., after recrystallization from methyl ethyl ketone. The filtrate wasevaporated to dryness under reduced pressure. From the residue there wascrystallized another 4.3. g. of suberic acid.

EXAMPLE 1v Example III was repeated with a charge consisting of 1.25 g.of the dilactone, 100 ml. of dimethylformamide, and 0.03 g. of platinumoxide catalyst. The hydrogenation was carried on at 45 1b./sq. in. for6.5 hours. Absorption corresponded to 66%of theoretical. 'Ihe filteredproduct was evaporated to dryness and the residue extracted withchloroform to give 0.26 g. of crude suberic acid.

The EA' -bifuranJ-5,5'-dione, used in Examples 1,111 and IV, wasprepared by charging into a steel pressure reactorof 400 cc. capacity 26g. of acetylene, 200 ml. of acetone, and 1.5 g. of dicobaltoctacarbonyl. The mixture was heated with carbon monoxide at a pressureof 1000 atmospheres for 1417 hours. The product was filtered and thebrown solid was extracted with ethyl acetate for 24 hours. The extractwas permitted to crystallizeand the crytalline material was separated,and dried at room temperature. There was obtained 20 g. of theunsaturated dilactone, C H O M. P. 229 C. after severalrecrystallizations from acetic acid.

The [A -bifuran]-5,5'-dione exists in the form of two structuralisomers; the normal or low melting form, 230-237" C. is the trans formand the high melting form, 240248 C. is the cis form. The formula ofthese structural isomers of [A bifuran]-5,5'- dione can be representedasfollows:

The di-n-butyldilactone, C H O used in Example II was prepared asfollows:

A pressure reactor was charged with ml. of acetone, 2 g. of cobaltcarbonyl, and 82 g. of n-butylacetylone, and the charge heated at 95120C. under a carbon monoxide pressure of 700900 atmospheres. Theseconditions were maintained for 18 hours, during which time the pressurewas maintained at the indicated level by periodically repressuring withcarbon monoxide. The crude reaction mixture was discharged from thereactor and distilled. The product from the fraction distilling at 205C./2 mm. crystallized upon standing. A portion of the distillate wasrecrystallized from petroleum ether containing a small amount of ethylacetate. After two recrystallizations the cream colored solid had ablock melting point of 124 C. and was found to analyze as follows: 7

Analysis.Calcd. for C H O C, 69.50; H, 7.30; M. W., 276. Found: C,69.20; H, 7.36; M. W., 270, 270.

The ultraviolet absorption spectra show a strong peak at 3475 A. and aweak peak at 2600 A. (the specific absorptivity k .:l44), whichcorresponds closely to the spectra of the unsubstituted dilactone.

The dilactones employed in this invention correspond to C (RR) O whereinthe R and R are hydrogen, alkoxyaryl, especially where the alkoxyradical is not more than 12 carbon atoms and the aryl radical ishydrocarbon of not more than 10 carbon atoms, haloaryl, especiallychloroaryl where the aryl radical is hydrocarbon of not more than 10carbon atoms, or monovalenthydrocarbon radicals free from non-aromaticunsaturation, especially of not more than 12 carbon atoms, e. g., alkyl,especially short chain alkyl, i. e., containing less than 7 carbonatoms, aryl, especially where the aryl radical is hydrocarbon of notmore than 7 carbon atoms, aralkyl, especially of not more than 7 carbonatoms, or cycloalkyl, particularly of not more than 7 carbon atoms.Examples of such radicals are methyl, ethyl, octyl, decyl, dodecyl,phenyl, tolyl, xylyl, benzyl, cyclohexyl, naphthyl, methylcyclohexyl,methoxyphenyl, ethoxyphenyl, decyloxyphenyl, dodecyloxyphenyl,dodecycloxynaphthyl, chlorophenyl, chloronaphthyl, and the like. Thesedilactones show strong lines in the ultraviolet spectra in the region of3300400 A. and yield suberic acids on hydrogenation over platinum inacetic acid.

These unsaturated dilactones can be represented by the where one of thering doubly bonded carbon atoms has its free valence satisfied by R andthe other of the ring doubly bonded carbon atoms has its free valencesatisfied by R, with R and R being defined as aforesaid.

As illustrative of these new dilactones corresponding to the formula C(RR') O there are disclosed in my copending application Serial No.549,155, the following substituted dilactones:

When these substituted dilactones replace the dilactone of Example I inthe process of Example I, there are obtained the correspondingsubstituted l,8-octanedioic acids, i. e., the corresponding substitutedsuberic acids.

The process of this invention is a marked advance over previously knownmethods for preparing 1,8-octanedioic acids, particularly suberic acid,in that it makes it possible to prepare suberic acid and substitutedsuberic acids in two steps from cheap, abundantly available acetylenesand carbon monoxide. Thus, the process not only makes suberic acidreadily available at a potentially low cost, but also makes accessibleother 1,8-octanedioic acids containing hydrocarbon substituents hithertoavailable only by tedious, complicated, expensive procedures.

Long chain dibasic acids such as suberic acid and substituted subericacids, are valuable products for the preparation of polyesters which arefiber forming.

As many apparently widely ditferent embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that this invention is not limited to the specificembodiments thereof except as defined in the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. Process for preparing a 1,8-octanedioic acid which compriseshydrogenating, in solution in a polar organic solvent and in contactwith a platinum catalyst, a dilactone represented by the general formulawherein one of the ring doubly bonded carbon atoms has its free valencesatisfied by R and the other of the ring doubly bonded carbon atoms hasits free valence satisfied by R', said R and R being selected from theclass consisting of hydrogen, .alkoxyaryl where the alkoxy radical isnot more than 12 carbon atoms and the aryl radical is hydrocarbon of notmore than carbon atoms, haloaryl where the aryl radical is hydrocarbonof not more than 10 carbon atoms, and monovalent hydrocarbon radicals,free from non-aromatic unsaturation, of not more than 12 carton atoms,and obtaining a 1,8-octanedioic acid as the resulting product.

2. Process for preparing suberic acid which comprises hydrogenating thedilactone [A -bifuran]-5,5'-

dione in solution in a polar organic solvent and in contact with aplatinum catalyst, and obtaining suberic acid as the resulting product.

3. Process for preparing suberic acid as set forth in claim 2 whereinsaid platinum catalyst is a platinum oxide catalyst.

4. Process for preparing suberic acid as set forth in claim 2 whereinsaid platinum catalyst is platinum chloride-on-charcoal.

5. Process for preparing suberic acid as set forth in claim 2 whereinsaid polar organic solvent is acetic acid.

6. Process for preparing suberic acid which comprises hydrogenating, ata temperature of 0 to C., under a pressure from atmospheric to 500lbs/sq. in., the dilactone [A -bufuran]-5,5'-dione in solution in apolar organic solvent and in contact with a platinum catalyst, andobtaining suberic acid as the resulting product.

7. Process for preparing suberic acid which comprises hydrogenating, ata temperature from room temperature of about 25 C. to 50 C., thedilactone [A bifuran]-5,5'-dione in solution in a liquid polar organicsolvent selected from the class consisting of acetic acid, dioxane,ethyl acetate, tetr-ahydrofuran, dimethylformamide and ethylene glycoldiacetate, and in contact with a platinum catalyst, and obtainingsuberic acid as the resulting product.

8. Process for preparing suberic acid which comprises hydrogenating, ata temperature of 0 to 50 C., under a pressure from atmospheric to 500lbs./ sq. in., the dilactone [A -bifuran]-5,5-dione in solution inacetic acid and in contact with a platinum oxide catalyst, and obtainingsuberic acid as the resulting product.

References Cited in the file of this patent UNITED STATES PATENTS2,484,497 Hagemeyer Oct. 11, 1949 OTHER REFERENCES Berkman et al.:Catalysis, 1940, page 818.

1. PROCESS FOR PREPARING A 1,8-OCTANEDIOIC ACID WHICH COMPRISESHYDROGENATING, IN SOLUTION IN A POLAR ORGANIC SOLVENT AND IN CONTACTWITH A PLATINUM CATALYST, A DILACTONE REPRESENTED BY THE GENERAL FORMULA